Poster 18: The genetics of marine organisms of the Belgian continental shelf

We address at two levels the question whether the structuring of the ecosystem of the Belgian continental shelf (BCS) is reflected in the genetic diversity and structuring of its marine taxa. First, we study the phylogenetic relationships of gobies from the genus Pomatoschistus using mtDNA sequencing. They are among the most abundant species of the BCS. Phylogenetic analysis has shown that this genus forms an interesting complex of species showing different degrees of relatedness and niche overlap. These fish species are parasitized by monogeneans of the genus Gyrodactylus. There is a remarkable congruence between the phylogenies of the host and some of its parasites, although some host switches can be found as well. Secondly, we go down to the population level of the sand gobies. P. minutus displays a high level of diversity and a pattern of genetic homogeneity, which might be attributed to larval dispersal, at least on a scale of tens of kilometres. P. lozanoi occupies a more specialized niche and its genetic diversity is higher. There is a clear inshore-offshore gradient on the BCS, maybe due to selection. We conclude that the genetic biodiversity of the BCS closely reflects the marine landscape with its diversity of niches.